JPS6299634A - Turbo-compound internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the efficiency of a recovery turbine at a low engine speed range, by halving a scroll passage of the recovery turbine connected to a turbosupercharger, and installing an on-off valve being opened or closed according to inlet pressure, in the other one. CONSTITUTION:A recovery turbine 2 is connected to the downstream side of the turbosupercharger 1 installed in an engine 1. The inside of a scroll of the turbine is divided into two parts, and an on-off valve 7 is installed in one side passage (a). This on-off valve 7 is controlled for its open or close by a controller 11 after detecting a scroll inlet pressure signal out of a pressure sensor 8. When an engine speed is low and inlet pressure in the turbine 2 is also low, the on-off valve 7 is closed, heightening the inlet pressure to some extent, thus turbine efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a turbo compound internal combustion engine.

(Prior Art) In a turbo supercharger used in a vehicle internal combustion engine, the exhaust flow rate is generally insufficient at a certain low rotation speed, and sufficient performance cannot be obtained. That is, As shown in Figure 3,
The inlet pressure P1 and outlet pressure P2 with respect to the exhaust flow rate to the turbocharger have a large influence as shown in the upper part of Fig. 3. Therefore, in a vehicle internal combustion engine in which the exhaust flow rate changes over a wide range, It is very difficult to use exhaust energy for intake supercharging or to recover it as power to the crankshaft.

Conventionally, in order to obtain sufficient intake supercharging against changes in exhaust flow rate, there is a method disclosed in Japanese Patent Laid-Open No. 58-79622. In this prior art, the recovery turbine inlet passage is
A control valve is installed in one of the passages, and when the exhaust flow i of the exhaust gas is small, the intake pressure of the turbocharger IM closes the 111 valve and supplies the exhaust from the passage to the recovery turbine. However, this method is difficult to apply to turbo compound internal combustion engines because it simply narrows down the turbine inlet of the turbocharger to increase the exhaust flow velocity and increase the turbine rotation speed.

In a turbo compound internal combustion engine where the exhaust gas from the turbocharger is introduced into the recovery turbine and the rotation of the recovery turbine is transmitted to the crankshaft of the first engine, the selection of the pressure ratio between the turbocharger III and the recovery turbine is particularly important. This is a major factor.

To elaborate on this point, at high angle loading point A where the turbocharger has a sufficient pressure ratio as shown in Figure 3, the pressure ratio of the recovery turbine can also be maintained sufficiently high as shown at point B. . However, if the exhaust flow rate is low, the pressure ratio of the turbocharger will also be low, as shown by the 0 point.
At the recovery turbine the pressure ratio becomes lower as shown at point LJD. Therefore, in order to increase the pressure ratio of the recovery turbine, it is important to shift the recovery turbine characteristics to point E in FIG. 3.

[Problems to be Solved by the Invention] An object of the present invention is to increase the pressure ratio of the recovery turbine by changing the nozzle passage area of the recovery turbine in order to satisfy the above-mentioned requirements. However, the object of the present invention is to provide a turbo compound internal combustion engine that increases the efficiency of the recovery turbine and transmits power to the engine's crankshaft.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention is to divide the turbine scroll passage of the recovery turbine into which the exhaust gas that has passed through the turbocharger is introduced, and to provide an on-off valve in one passage. and means for closing the on-off valve at an engine speed with a low exhaust flow rate.

[Operation] Since the exhaust flow rate is small at low rotational speeds of the engine, one of the scroll passages divided by the partition plate 6 is closed by the on-off valve 7. This increases the inlet pressure, increases the pressure ratio, and significantly increases the rotational speed of the recovery turbine 2.
Efficiency is also high, and the recovery turbine 2 (9-shaped shaft 1
8 rotation is transmitted to the engine crankshaft.

[Examples of the Invention] The present invention will be described based on Examples. As shown in FIG. 1, a turbocharger n1 is connected to the exhaust pipe 3 of the internal combustion engine 17, and the exhaust gas supplied to the turbocharger 1 rotates a turbine, which drives a blower. , intake supercharging is performed. Then, the exhaust gas discharged from the turbocharger 1 passes through the turbine scroll 4, enters the scroll chambers 13a and 13b of the recovery turbine 2, hits the turbine blades 12, rotates this shaft 18, and is discharged into the exhaust pipe 19. .

According to the present invention, the turbine scroll 4 is divided into two by the partition plate 6 into the scroll passage a and the scroll passage
An on-off valve 7 is disposed in one scroll passage a. During this time, the lever 10 is connected to the shaft 21 of the valve opening 7 and is driven by the electromagnetic actuator 9. Then, an electric signal from a pressure sensor 8 provided at the inlet of the turbine scroll 4 is input to an electronic control unit 11, and when this pressure saw becomes less than a predetermined value, an electromagnetic actuator 9 is excited by the output of the electronic control unit 11. Then, the rod 9a is extended and the on-off valve 7 closes the scroll passage a.

A generator 14 is attached to the shaft 18 of the recovery turbine 2 . That is, while the rotor 15 is coupled to the shaft 1B,
A stator 16 is arranged around this. The electric power generated by the generator is then supplied to a transmission machine connected to the crankshaft of the engine. However, instead of providing a generator, the shaft 18 of the recovery turbine 2 is
The rotation of the engine may be transmitted to the crankshaft of the engine. Alternatively, a recovery turbine 3 may be connected to the exhaust pipe 3, and a turbo supercharger 1 may be connected to the outlet side of the recovery turbine 2.

As the engine speed increases, the exhaust flow rate also increases, and when the pressure detected by the pressure sensor 8 exceeds a predetermined value, the rod 9a of the electromagnetic actuator 9 is returned by the restoring force of a spring (not shown), and the lever 10 is In FIG. 2, the on-off valve 7 is opened by being rotated counterclockwise. Therefore, the scroll chambers 13a and 13b are connected to each other from both the scroll passages a and b.
Exhaust gas flows into the turbine blade 12, and the rotational speed and torque of the turbine blade 12 increase. At this time, the inlet pressure of the recovery turbine 2 increases, the pressure ratio P4/P3 increases, and the recovery turbine 2 approaches point B shown in FIG. 3.

When the pressure ratio of the recovery turbine 2 increases, the exhaust pressure of the turbocharger turbine increases. That is, the pressure ratio is P4
/P3 to P4'/P3', and the inlet pressure of the recovery turbine 2 is PI = (Pi /P2)xp 4''
Therefore, the exhaust stroke work of the engine increases by the amount of increase in exhaust pressure. This increase in workload and the improvement in efficiency of the recovery turbine 2 are in a contradictory relationship. Therefore, the turbine of the turbocharger can also have the same structure as the recovery turbine 2.

[Effects of the Invention] As described above, the present invention provides two scroll passages on the inlet side of the recovery turbine, that is, on the turbine scroll, by using a partition plate.
The scroll passage is divided into two sections, and one scroll passage is equipped with an on-off valve that opens and closes in response to changes in population pressure.When the engine speed is low and the exhaust flow rate is low, the on-off valve is closed and the scroll on one side is closed. By introducing exhaust gas from the passage into the recovery turbine, the inlet pressure can be increased, increasing the rotation speed of the recovery turbine and suppressing a decrease in efficiency. By opening the on-off valve and introducing exhaust gas from both scroll passages to the recovery turbine, exhaust energy can be completely absorbed. Electric power from a generator connected to the recovery turbine 2 is then supplied to a conductor connected to the crankshaft of the engine.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a turbo compound internal combustion engine according to the present invention, Fig. 2 is a cutaway side view of a recovery turbine in the turbo compound internal combustion engine, and Fig. 3 shows the operation of the turbo compound internal combustion engine. It is a diagram for explaining.

Claims (1)

[Claims] The turbine scroll passage of the recovery turbine that introduces the exhaust gas that has passed through the turbocharger is divided, one passage is provided with an on-off valve, and means is provided for closing the on-off valve at an engine speed with a small exhaust flow rate. Features a turbo compound internal combustion engine.